The introductory tutorial section of the first edition was almost
completely removed in the second version. There was still explanatory
material, of course, but it was very definitely aimed at the
experienced programmer. While there is nothing to inherently preclude
the "definitive" claim, the style of the book is much closer to
"JavaScript in a Nutshell." This format and style is maintained in
the third edition.

The book is divided into "core JavaScript", "client-side JavaScript",
and a reference section. "Client-side" scripting is, of course,
interpreted and run by the client, or browser. Many servers are now
capable of using JavaScript in server side processing, as a
replacement or enhancement for CGI (Common Gateway Interface)
programming. Thus the division into the core functions, which can be
interpreted by either client or server, and the Web page specific, or
some advanced, functions which can only be handled by the client. The
reference, taking up approximately half of the book, is as one would
expect.

Flanagan has collected, and presents, a good deal of solid information
about JavaScript. However, the material can be oddly uncritical.
Flanagan notes, for example, that JavaScript is more functional than
might be indicated by the "script" term, and is a full object-oriented
programming language, with all the complexity required by that type of
entity. Some of the intricacy involved in using JavaScript, though,
arises from inconsistencies in approach. It is fairly clear that
JavaScript was partly intended to be simple, and partly intended to be
capable. JavaScript security also gets the benefit of the doubt.

The claim to definitive status is quite supportable, however.
Flanagan presents all kinds of information about the oddities of the
language, weird behaviours that arise from interpretations of
variables and operators. The book reveals the internals of the
language (or languages, given the number of variants), which are
bewildering in their complexity.